Drop-on-demand inkjet printing systems eject ink droplets from printhead nozzles in response to pressure pulses generated within the printhead by either piezoelectric devices or thermal transducers, such as resistors. The ejected ink droplets, commonly referred to as pixels, are propelled to specific locations on an image receiving member where each ink droplet forms a spot on the member. The printheads include a faceplate having a plurality of droplet ejecting nozzles and a plurality of ink containing channels, typically one channel for each nozzle, which interconnect an ink reservoir in the print head with the nozzles.
In a typical piezoelectric inkjet printing system, the pressure pulses that eject liquid ink droplets are produced by applying an electric pulse to the piezoelectric devices, one of which is located within each of the inkjet channels. Each piezoelectric device is individually addressable to enable a firing signal to be generated and delivered for each piezoelectric device. The piezoelectric device deforms in response to receiving the firing signal, pressurizing a volume of liquid ink adjacent the piezoelectric device. As the ink is pressurized in a selected channel, a quantity of ink is displaced from the channel and a droplet of ink is mechanically ejected from the nozzle. The ejected droplets form an image on the image receiving member opposite the printhead. The respective channels from which the ink droplets are ejected are refilled by capillary action from an ink supply.
In some printers, the image receiving member is a rotating drum or belt coated with a release agent and the ink is a phase-change ink, which is solid at room temperature and transitions to a liquid phase at an elevated temperature. The printhead ejects droplets of liquid phase-change ink onto the rotating image receiving member to form an image, which is then transferred to a recording medium, such as paper. A drum maintenance unit or other release agent applicator prepares the image receiving member for receipt of the ejected ink by applying a layer of release agent to an imaging area on the image receiving member. The layer of release agent on the image receiving member forms a surface on which the ink image is formed and facilitates the transfer of the ink image from the receiving member to a recording medium. The transfer is generally conducted in a nip formed by the rotating image member and a rotating pressure roller, which is also known as a transfix roller. As the recording medium is transported through the nip, the fully formed image is transferred from the image receiving member to the recording medium and concurrently fixed thereon. This technique of using heat and pressure at a nip to transfer and fix an image to a recording medium passing through the nip is typically known as “transfixing.”
The time required for image generation and transfer is controlled in an indirect printer by the frequency at which the inkjet ejectors can be operated, the overhead operations required to prepare the image receiving member and transfer the image from the image receiving member to recording media, and the number of revolutions of the image drum required for these processes. Reducing the number of revolutions of the image receiving member needed for each print can reduce the time required to print an image. Thus, printing in a manner that reduces the number of revolutions of the image receiving member would be beneficial to improved printer throughput.